The study succeeded in producing a chicken-flavored fried TSP that was deemed to acceptable by consumers, state the researchers in the Journal of Food Science .
The European market from meat-free and tofu products was valued at €1.2bn in 2006, a five per cent increase on the previous year, according to Prosoy, a research and strategy consultancy.
However, according to the researchers, the main limitation that has prevented the use of large concentrations of TSP has been an undesirable "beany" flavour or odour.
"The undesirable beany flavour or odour is a result of the oxidation of unsaturated fatty acids by lipoxygenase enzymes during processing of soy protein products," explained the Iowa State researchers.
"After the hydration process, the TSP has a sponge-like structure.
This fibrous structure is the other challenge… because it makes the products too chewy compared with real poultry or meat products," they added.
M. Katayama and L.A. Wilson investigated the best formulation of textured soy protein TSP and vegetable-based flavours to produce "chicken" or "shrimp" flavoured TSP.
The acceptability of the TSP was then analysed by a minimum of 14 trained panellists.
Baked or deep-fat fried TSPs were soaked in five different commercial vegetable-based powered, liquid, or oil-based flavours.
For chicken flavour, concentrations ranging from 16.7 to 22.3 per cent were tested, while shrimp flavour concentrations ranged from 1.0 to 22.2 per cent.
The researchers used four types of commercial TSP with an average protein content of 51 per cent.
Three simple steps produced the products - hydration with the flavour solution, chilling a short time, and finally frying or baking of the TSP.
The researchers report that crouton-shaped bits (BITs) impregnated with flavour exhibited the greatest crispness, while the chicken flavour powder produced a more intense flavour, as assessed by the consumer panel.
"This study succeeded in the utilization of the soybean components through the development of chicken-flavoured fried TSP that was accepted by the consumers," wrote Katayama and Wilson.
"The plant-based ingredient formulation developed in this study allows easy incorporation of the TSP products into the diet as stand-alone products or ingredients.
It can be marketed inside and outside of the United States," they added.
In terms of future studies, they added that the use of soybeans would be seen as more functional and economical.
"It will provide benefits that can contribute to consumers as per the results of this study," they concluded.
Source: Journal of Food Science Published online ahead of print, OnlineEarly Articles , doi:10.1111/j.1750-3841.2008.00663.x "Utilization of Soybeans and Their Components through the Development of Textured Soy Protein Foods" Authors: M. Katayama, L.A. Wilson